1. Field of the Invention
This invention relates to a process of producing .alpha.-keto acids having the general formula RCOCOOH wherein R is substituted or unsubstituted aryl, alkenyl or heterocyclic group, in which an organic halogenide is carbonylated by the reaction with carbon monoxide and water in the presence of a basic compound and a palladium containing catalyst.
2. Description of the Prior Art
It is known that .alpha.-keto acids are important intermediate compounds to prepare many useful products such as .alpha.-amino acids, medicines, agricultural chemicals, polymerization initiators and other chemical products. Hitherto, such .alpha.-keto acids have been prepared by hydrolysis of acyl cyanides. For synthesis of acyl cyanide themselves, a toxic heavy metal cyanide is heat-reacted with an expensive acyl halide at an elevated temperature for a long period of time. Besides, the hydrolysis of acyl cyanide accompanies undesired side reactions through which organic acids and prussic acid are by-produced. The known processes are accordingly disadvantageous from the industrial viewpoint.
It is also known that .alpha.-keto acids are obtained by hydrolyzing hydantoin derivatives in the presence of an alkali catalyst. The hydantoin derivatives, however, are very expensive and this process is not favorable for industrial applications.